Let us briefly outline the main differences in DV-polarization teleportation relative to CV teleportation.
In DV-polarization implementations the vacuum contribution does not enter the teleportation channel in the same manner it does in a CV entangled channel. In the DV-polarization channel the loss enters our calculations primarily via two avenues. One avenue is simply through the different raw detection rates set by the differential evolution of the beam profiles in the downlink and uplink. As discussed, in the downlink the beam width at the receiver will be smaller than in the uplink. For a given receiver aperture this translates into an increased detection rate in and by itself. We can use the phase screen calculations described earlier (e.g. Fig. REF  for equal transmit and receive apertures of 1m) to determine this rate increase. The second avenue is a manifestation of the vacuum through dark counts in the photodetectors. In real-world deployments of teleportation through long free-space channels [1]}, [2]}, [3]} a coincidence counter is used to pair up entangled photons, typically with a time-bin width of 3ns [1]}. Due to the presence of a vacuum in almost all time-bins, only of order 1 in a million events are triggered as a photon-entangled pair. Dark counts in the best photodetectors are currently in the range of 20Hz. However, in orbit, and because of stray light, combined background counts are more likely to be of order 150Hz [1]}. A background count in one time-bin will lead to a false identification of an entangled pair generated between the satellite and ground station. This is different to the CV scenario where each time bin is assumed to contain a pulse - albeit one contaminated with a vacuum contribution.
